For convenience I'll post the full text as available from the UK Government's site this morning:

5Preparation of terrorist acts(1)A person commits an offence if, with the intention of—
(a)committing acts of terrorism, or
(b)assisting another to commit such acts,he engages in any conduct in preparation for giving effect to his intention.
(2)It is irrelevant for the purposes of subsection (1) whether the intention and preparations relate to one or more particular acts of terrorism, acts of terrorism of a particular description or acts of terrorism generally.
(3)A person guilty of an offence under this section shall be liable, on conviction on indictment, to imprisonment for life.

Basically, assisting anyone else to commit acts of terrorism is a criminal offence in UK Law. It's difficult, for example, to argue that supplying arms is for purely humanitarian purposes.

The punishment for such an offence contrary to Section 5 is imprisonment for life. So it's not a trivial matter.

So, if my analysis is correct, those "assisting" Syrian rebels to commit acts of terrorism can be imprisoned for life.

Will David Cameron and William Hague be locked up? If the Law was applied equally and we had honest senior Police officers in this country (which isn't a given) it seems to me that Cameron and Hague (as well as many others) should be locked up, if they arm those in Syria who are committing acts of terorism.

But the criminality, as I see it, of arming the Syrian rebels may raise other interesting questions.

Would Members of Parliament who vote for the UK to commit offences contrary to Section 5 of the Terrorism Act 2006 also be committing an offence?

A vote in favour of arming the Syrian rebels would be, on the face of it, "assisting" the arming of the Syrian rebels. I don't think that there's much doubt about MPs voting for arming the rebels having "assisted" them.

Can MPs be arrested for committing terrorist offences?

Are MPs immune from prosecuction on such matters?

Does "parliamentary privilege" extend to immunity from arrest and prosecution for a Section 5 terrorist offence? I suspect not.

It would be an interesting constitutional and legal debate.

An interesting political debate too. Not least after some of the flamboyant outpourings against terrorism from some Members of the House of Commons.

If the House of Commons did vote for arming the Syrian rebels could it fairly be called the House of Terrorists?

40 Terrorist: interpretation.

(a)has committed an offence under any of sections 11, 12, 15 to 18, 54 and 56 to 63, or

(b)is or has been concerned in the commission, preparation or instigation of acts of terrorism.

(2)The
reference in subsection (1)(b) to a person who has been concerned in
the commission, preparation or instigation of acts of terrorism includes
a reference to a person who has been, whether before or after the
passing of this Act, concerned in the commission, preparation or
instigation of acts of terrorism within the meaning given by section 1.

I have underlined the relevant parts of the Section.

MPs voting for arming the rebels would, at least arguably, have been "concerned in the ... preparation ... of acts of terrorism", wouldn't they?

Is arming the Syrian rebels a criminal offence under UK Law? Yes

What is the punishment on conviction? Imprisonment for life.

It will be interesting to see how my meeting with my MP goes later today.